1. Field of the Invention
The present invention relates to a portable data-processing apparatus, such as a portable computer and a portable word processor, into which data can be input by using a pen. More particularly the invention relates to a battery pack for use as a power supply in the portable data-processing apparatus.
2. Description of the Related Art
Recently there have been developed portable computers which has a pressure-sensitive tablet designed for use in place of a keyboard and into which data is input by touching the tablet with a pen. A computer of this type comprises a flat box-shaped housing and a pressure-sensitive tablet. The housing has a flat upper surface, at which the input screen of the tablet is exposed. The computer has a battery pack used as a power supply for driving other components of the computer, and can therefore be used in any place where a commercial power supply is not available. The battery pack is removably placed in the battery receptacle formed in the bottom of the computer housing, while placed in the housing, the battery pack has its bottom and sides located flush with the bottom and sides of the housing and, hence, appears as if it were a part of the computer housing.
The housing of the portable computer described above is so compact that the computer is easy to carry with. The battery pack is also made small, occupying but a smallest space possible in the computer housing. It is smaller than those designed for use in book-sized computers having a keyboard.
The smaller the battery pack, the smaller the power-storage capacity thereof, and the shorter the time for which the portable computer can be used continuously. To use the computer for a relatively long time in a place where no commercial power supply is available, a user must set two or more battery packs in the computer housing. However, the computer housing of a limited size cannot have a space large enough to accommodate two or more battery packs. There has been a demand for a battery pack which is compact enough to be used in a pen-input type portable computer and which has a power-storage capacity great enough to drive the computer for a long time.